public function postAddProduct()
 {
     $request = Input::all();
     $validator = Validator::make($request, ['name' => 'required|max:255', 'cat' => 'required']);
     if ($validator->fails()) {
         $this->throwValidationException($request, $validator);
         die;
     }
     unset($request['_token']);
     $result = Product::create($request);
     $result = $result->toArray();
     $request['id_product'] = $result['id_product'];
     if ($request['category'] == 'laptop') {
         Laptop::create($request);
     } elseif ($request['category'] == 'laptop') {
         Book::create($request);
     }
     return redirect('/admin/product/add');
 }